1. Field of the Invention
The present invention relates to a light emitting diode (LED) assembly, and more particularly to an LED assembly having separated thermal and electrical structures for ensuring a constant lighting brightness and a long lifetime thereof.
2. Description of Related Art
LED have been available since the early 1960's. Because of the relatively high efficiency of LEDs, nowadays LED usage has been increased in popularity in a variety of applications, e.g., residential, traffic, commercial, industrial settings. However, when the LED is in operation, it generates a great deal of heat, which may result in the LED overheating or even malfunction if the heat cannot be dissipated timely. Therefore, many attempts are tried in order to effectively cool the LED.
U.S. Pat. No. 6,561,680 B1 discloses a type of LED assembly, which comprises a metal substrate and an LED attached on the substrate (see FIG. 1B of U.S. Pat. No. 6,561,680 B1). The LED has an anode portion and a cathode portion electrically connecting an LED die to a power source to forward a current into the LED die. The anode portion and the cathode portion also thermally contact the substrate in order to dissipate heat from the LED die. When the LED is working, the current is carried to the LED die via the cathode and anode portions from the substrate; simultaneously, the heat generated by the LED die is also transferred to the substrate by the cathode and anode portions, thereby to ensure that a temperature of the LED die is controlled within its normal range.
Nonetheless, there is a problem in this type of LED assembly: since both of the current flux and the heat flux are transferred via the anode and the cathode portions and the substrate, a current transferring pathway of the LED assembly substantially overlaps a heat conducting pathway thereof; thus, the current is easily influenced by the heat. As the temperature of the anode and the cathode portions reaches a high level, the influence of the heat acting on the current becomes significant and results in the current flowing through the anode and cathode portions unstable and fluctuating. The unstable current renders the light emitted from the LEDs flickering, whereby an illumination provided by the LED assembly deteriorates. Furthermore, this unstable current input into the LED may significantly lower a lifetime of the LED; thus, this type of conventional LED assembly cannot be utilized for a sufficiently long period of time.
What is needed, therefore, is an LED assembly which can overcome the above-mentioned disadvantages.